Dice mechanics
Percentile (d100) checks in Call of Cthulhu 7th Edition
Roll under skill mechanics and difficulty bands.
Explanation
Call of Cthulhu uses percentile skills: roll d100 and succeed if you roll at or under your skill. Difficulty often shifts the threshold (Regular/Hard/Extreme) and Sanity loss is a core pressure loop.
At the table (quick loop)
- Pick the relevant skill (e.g., Spot Hidden, Library Use).
- Roll d100 and compare to your skill rating (and difficulty threshold).
- Apply consequences: information gained, complications, or Sanity loss when appropriate.
Example: Spot Hidden 55%: a roll of 42 succeeds; a harder threshold would require a lower roll.
Examples
Example: skill target
Spot Hidden 55%: roll 55 or under to succeed. Hard = 27 or under. Extreme = 11 or under.
Example: fail forward
If the clue matters, don't block progress on failure. Trade success for time, noise, or a new complication.
Common mistakes
- Mistake: Forgetting difficulty bands. Fix: Use Regular/Hard/Extreme (or your table’s bands) to express stakes quickly.
- Mistake: Failure stops the investigation. Fix: Fail forward: you still get something, but pay a cost.